Pressure-reducing element for splitting the recooling volume flow in sorption machines

ABSTRACT

The invention relates to the use of a pressure-reducing element or splitting volume flows in a sorption machine, wherein a single volume flow from a recooling device is split into at least two volume flows. A first volume flow flows through at least one tube of a first tube section into a condenser and a second volume flow through at least one tube of a second tube section into an absorber, at least one of the two tube sections leading away from the recooling device or at least one of the two tube sections leading back to the recooling device comprising at least one pressure-reducing element.

The invention relates to the use of a pressure-reducing element for splitting volume flows in a sorption machine as well as in an adsorption refrigerating machine and to a method of splitting the volume flows in a sorption machine.

Refrigerating machines generally used for heating and/or cooling buildings have been described in the prior art. Refrigerating machines carry out thermodynamic cycles wherein e.g. heat is absorbed below ambient temperature and rejected at elevated temperature. The thermodynamic cycles are similar to those of a heat pump. Refrigerating machines well-known in the prior art are e.g. adsorption refrigeration systems, diffusion-absorption refrigerating machines, adsorption refrigeration systems or solid sorption heat pumps and compression refrigeration systems.

An adsorption refrigerating machine consists of an adsorber/desorber unit, an evaporator, a condenser and/or a combined evaporator/condenser unit housed in a single container or in separate containers that are connected to pipes etc. for refrigerant flow. The advantage of sorption machines over conventional heat pump technology is that adsorption/desorption solely proceeds via temperature control of the sorbent. As a consequence, the container of the adsorption machine can be sealed in a hermetic and gas-tight manner. When using water as refrigerant, for example, the adsorption refrigerating machine preferably operates in a vacuum range. The refrigerant density in the vacuum range is very low, so that the flow rates of the vaporous refrigerant can be very high in some cases (e.g. 25 m/s-100 m/s or higher). Accordingly, the vapor flows inside an adsorption machine require careful design so as to avoid unnecessary pressure loss of the vapor flow.

Adsorption proceeding in an adsorption machine represents a physical process wherein a gaseous refrigerant (e.g. water) binds to a solid, during which binding energy is transferred from the refrigerant to the solid. On the other hand, energy is required in the desorption of the refrigerant, i.e. removal of the refrigerant from the solid. In an adsorption refrigerating machine, the refrigerant absorbing heat at low temperature and low pressure and rejecting heat at elevated temperature and pressure is selected in such a way that adsorption and desorption are accompanied by a change of state. Materials which are finely porous and therefore have a very large internal surface area have been described as adsorbents in the prior art. Advantageous materials are activated charcoal, zeolites, alumina, or silica gel, aluminum phosphates, silica-aluminum phosphates, metal silica-aluminum phosphates, mesostructure silicates, organometallic frameworks and/or microporous materials comprising microporous polymers.

The heat of adsorption and heat of condensation must be removed from the system during the process in the adsorption machine. This is usually done using a flowing heat carrier medium that transports the heat to a heat sink, e.g. a closed-circuit cooling unit, which releases the heat into the ambient air. If, however, removal of the adsorption heat and/or condensation heat is poor or non-existent, the temperature and thus the pressure inside the adsorption machine would rise and the adsorption process would come to a standstill. As a result of improved heat transfer, the efficiency of an adsorption machine can be increased significantly, which inevitably improves the economic viability of the system.

A number of different sorption machines wherein the heat-carrying medium usually flows through a line including heat exchangers (adsorber or condenser), hydraulic piping, hydraulic components (e.g. valves) have been disclosed in the prior art. For example, DE 32 07 435 A1 describes a controlling and regulating device for a sorption heat pump. The controlling and regulating device measures the temperature in the circulation of a service fluid and adjusts the volume flows in accordance with the temperature. Regulation of the flows proceeds using a three-way valve well-known in the prior art.

The document EP 0 152 931 discloses a generator-absorption heat pump heating system and a method for operating a generator-absorption heat pump heating system for room heating, hot water heating and the like. A reversing valve is integrated in the absorption heat pump, so that the heat-carrying fluid is alternately directed to an adsorber and a condenser.

In sorption machines disclosed in the prior art, the total volume flow of the heat-carrying medium arriving from the recooler is usually split into a flow passing through the adsorber and a flow passing through the condenser. Depending on the volume flow splitting, different temperatures of adsorber and condenser can thus occur, especially towards the end of the recooling phases. However, depending on operating point, mode of operation, built-in components, or installation configuration, identical or different cooling of adsorber and/or condenser can be advantageous.

To accomplish this, the prior art has used splitting of the heat-carrying fluid from the recooler between the adsorber and condenser and parallel passage thereof through the adsorber and condenser, during which process the total volume flow remains constant. Depending on the pressure loss arising inside the adsorber and condenser and the associated pipe sections and hydraulic components (e.g. valves), the volume flow is distributed over both lines in such a way that the same pressure loss is present in both lines. When having one single layout of pressure losses in the lines, adjusting a specific operating point is only possible with a high degree of imprecision; intentional fine adjustment is not possible because e.g. commercial pipe nominal widths or valve sizes are only available in grades with respect to diameters. When both lines in the installation reach precisely predefined pressure losses, changing the layout volume flow is not possible without simultaneously influencing the level of pressure loss. Sorption machines disclosed in the prior art do not allow specific adaptation or optimization of volume flow splitting so that better performance or higher efficiency cannot be achieved in this way.

The object of the invention was therefore to achieve variable splitting of volume flows between adsorber and condenser, wherein the disadvantages of the prior art are absent and the performance of sorption machines can be improved.

Surprisingly, said object is accomplished by the features of the independent claims. Advantageous embodiments can be inferred from the subclaims.

It was surprising to find that a pressure-reducing element can be used for splitting volume flows in a sorption machine and that such splitting does not give rise to the drawbacks described in the prior art. According to the invention, a total volume flow from a recooling unit is split into at least two volume flows. A first volume flow flows through at least one pipe of a first pipe section into or through a condenser, and a second volume flow flows through at least one pipe of a second pipe section into or through an adsorber. At least one of the two pipes or pipe sections coming from or leading back to the recooling means has at least one pressure-reducing element. As a result, the two pipe sections or pipes advantageously have substantially different pressure loss coefficients. Advantageously and surprisingly, the pressure-reducing element is capable of influencing the ratio of pressure loss coefficients in both pipe sections. Surprisingly, the pressure-reducing element thus can adapt and/or establish the pressure loss coefficients in both pipe sections or lines. By using the pressure-reducing element it is possible, depending on operating point, mode of operation, built-in components, or installation configuration, to split the flows between adsorber or condenser or adapt or adjust the pressure loss coefficients of the pipe sections without requiring a technical modification. It is possible in this way to achieve technically simple and low-cost splitting of volume flows preferably between adsorber and condenser or adjustment of the pressure loss coefficients in the pipe sections. The volume flows or pressure loss coefficients can be adapted to various boundary conditions, operational phases and/or modes of operation, or even built-in components. The pressure-reducing element allows simple splitting of the volume flow ratio preferably between adsorber and condenser, thereby achieving in particular different cooling of adsorber and condenser. Those skilled in the art will be aware of the fact that pressure loss refers to the pressure difference resulting from wall friction and internal fluid friction in pipes. This implies that, owing to at least one pressure-reducing element, the pressure loss in the two lines from the recooler is preferably non-identical, that is, the pipe sections or volume flows have substantially different pressure losses or different pressure loss coefficients. With respect to the pressure loss, the expression “substantially” is not an obscure expression to a person skilled in the art because it is clear from the overall disclosure of the invention that the pressure losses are preferably different in the two volume flows and that this expression naturally encompasses small as well as large pressure losses. For example, the above-mentioned different pressures can be determined using measuring methods described in the prior art. Those skilled in the art will be familiar with the term “pressure loss coefficient” and the use thereof in connection with the teaching according to the invention. It can be preferred to integrate more than one pressure-reducing element in the pipes or pipe lines or pipe sections coming from the recooler. Advantageously, it is also possible to install the pressure-reducing elements in the pipes coming from the adsorber and/or condenser (i.e. the pipes leading back to the recooler or recooling means). This can be particularly advantageous in multi-chamber adsorption machines.

Those skilled in the art will be aware of the fact that operating points can define particular points in the characteristic diagram or on the characteristic curve of a technical device, preferably a sorption machine and more preferably an adsorption refrigerator or adsorption heater, which operating points are assumed as a result of system properties and exposure to external influences and parameters. Examples thereof are the temperatures of heat sinks and sources or total volume flows in the recooling circulation in the evaporator or in the desorber line.

Among those skilled in the art a volume flow is understood to be in particular the volume of a medium that moves through a cross-section of in particular a pipe or pipe section per unit time. As a consequence, the total volume flow comprises in particular the entirety of the volume flows preferably in a machine. In the meaning of the invention, “mode of operation” preferably refers to the way of conducting the operation of the machine. Examples include the adaptation of the sorption machine cycle times, that is, short cycle times can increase the performance of the machine, whereas prolonged cycle times result in higher efficiency.

The built-in components can be, for instance, adsorber heat exchangers provided with the same pressure but different adsorbent materials. Advantageously, the adsorbent material can be applied differently, that is, it can be a bed, a bonded and/or crystallized material. These different types of application allow adaptation of the adsorption machine to varying requirements. Thus, the machine can be adapted to a site or a refrigerant. In addition, the layer thickness of the adsorbent material is crucial for the performance of the adsorbent material.

In the meaning of the invention, “installation configuration” preferably refers to the configuration of the machine, that is, for example, the internal hydraulic circuitry of the machine components, the internal refrigerant-side interconnection of the components, or the modified basic structure of the machine (e.g. number of adsorbers, operation of evaporator, condenser etc.).

In the meaning of the invention, a recooler or recooling device refers to, in particular, a device preferably used to cool the heat-carrying fluid, i.e. dissipate the absorbed energy to another fluid or medium. For example, a recooler may comprise a geothermal heat exchanger, a swimming pool, a well or other device for cooling or absorbing thermal energy. The volume flow passing through the machine is preferably a heat-carrying fluid, i.e. a fluid capable of absorbing and rejecting energy in the form of heat. Preferred heat-carrying fluids comprise water or brine which are particularly beneficial for the environment and favorable in cost. In addition, the flow characteristics of water and brine are optimal for a sorption machine. Moreover, both represent a large heat reservoir, and rapid dissipation of heat is also possible.

Advantageously, the pressure-reducing element can be regulated or adjusted in such a way that, e.g. at the beginning or at the end of an operational phase, there is preferably no flow at all through one of the lines, and the entire volume flow passes through the other line. In this way, a component part or component can be cooled rapidly and effectively, and the performance or efficiency of the sorption machine is substantially improved. This represents a departure from conventional technologies and opens up a new technical field because technical adaptations to different modes of operation of a sorption machine, preferably an adsorption machine, are no longer required when using the pressure-reducing element. This in turn results in lower production costs and universal applicability of the machines.

The pressure-reducing element is advantageously integrated in a pipe such that the cross-section of flow is reduced and thus allows variable adjustment of the volume flow. Surprisingly, the pressure-reducing element produces particularly high efficiency, especially in adsorption machines comprising adsorption heaters and adsorption refrigerators. Particularly preferred are sorption machines wherein the condenser and/or adsorber are heat exchangers. A heat exchanger is a device which transfers thermal energy preferably from one flow of material to another.

Advantageously, the pressure-reducing element can be used in single-chamber systems, e.g. with two adsorbers, but also in two- or multi-chamber systems with only one adsorber per sorption machine, e.g. adsorption machine. In addition, easy and rapid adaptation to other types of sorption machines is possible. In general, no technical modification of the machines is required to this end.

The pressure-reducing element is preferably a throttle, a valve or a stopcock. The elements can be integrated in a pipe to cause local narrowing of the flow cross-section. Advantageously, various valves, which can be classified according to their geometric shape, can be integrated in the pipes. It is possible to use valves comprising straight-way valves, angle valves, angle seat valves and/or three-way valves. By using the valves, accurate and precise metering of flow through the pipes and safe shut-off against the environment is possible. Advantageously, the valves can be operated by hand, by medium, mechanically or electromagnetically, thereby allowing precise and safe control of the volume flows. A throttle in the meaning of the invention is preferably a conical piece of pipe within a pipe line, with concentric or eccentric reducers being preferred.

In another preferred embodiment the pressure-reducing element is a shutter and/or a mounting part. For example, a mounting part comprises a reduced cross-section of a piping or parts of the piping of a line, a T-piece with reduced branch, or a sleeve, shutter, fitting, or a measuring, regulating or controlling device with reduced cross-section. Those skilled in the art of rheology/fluid mechanics will know how to integrate such a mounting part in a pipe. Advantageously, the pressure-reducing or cross section-reducing elements can be integrated in one or more pipes, and it may be advantageous to impart them with an adjustable and variable design. That is, the pressure-reducing elements can be adjustable or self-regulating, so that optimum or preferred volume flow splitting can preferably be adjusted at any time under any boundary condition because the flow cross-section of the pipes can be made smaller or larger. In this way, the volume flowing through the pipe can be varied easily but effectively. For example, adjustability of the pressure-reducing element can be implemented by means of a manually operated cock. On the other hand, it may be preferred to have automatic and/or self-regulating adjustment of the pressure-reducing element and thus the flow cross-section of the pipe. To this end, the pressure-reducing element can be provided with measuring and controlling devices which measure e.g. the pressure inside the pipe and, based thereon, alter the nominal width of the pipe, i.e. the cross-section of the pipe, by means of the pressure-reducing element.

Thus, it may be preferable to have the pressure-reducing element alter the nominal width of the pipes or the pipe or the cross-section of free flow in such a way that volume flows having different and/or equal pressures are present in the heat exchanger, said heat exchanger preferably being the adsorber or the condenser.

In another preferred embodiment at least one measuring and/or regulating device is mounted between recooler and adsorber and/or condenser. The device measures in particular physical properties of the volume flow, comprising temperature, pressure and/or flow rate. Advantageously, the device is mounted on at least one pipe such that e.g. a measuring probe is present in the pipe and in contact with the fluid flowing through the pipe. The measured quantities are digitized and output in the form of data. Advantageously, it is also possible to store the measured data and make use thereof in comparative experiments, so that the sorption machine can be optimized. It may be preferable to compare the measured data, the so-called actual values, with predetermined target values, a possibly existing difference causing the regulating device to vary preferably the pipe nominal width or the cross-section of free flow via the pressure-reducing element. Continuous and largely trouble-free operation of the machine is possible in this way. Moreover, the machine can be rapidly and easily adapted to different modes of operation. To this end, the target values preferably correspond to values defining a specific mode of operation.

Similarly, the technical object is accomplished through the use of a pressure-reducing element which is used to split volume flows specifically in an adsorption machine. To this end, a total volume flow from a recooling unit is split into at least two volume flows, a first volume flow flowing through at least one pipe of a first pipe section into a condenser, and a second volume flow flowing through at least one additional pipe of a second pipe section into an adsorber. At least one of the two pipes or pipe sections coming from or leading back to the recooling means has at least one pressure-reducing element. Advantageously, the two pipe sections have substantially different pressure loss coefficients. It was completely surprising that a pressure-reducing element integrated in at least one pipe or pipe section of an adsorption machine, preferably an adsorption refrigerating machine, more preferably an adsorption heater, is capable of splitting the volume flows between adsorber and condenser, so that the mode of operation of the machine can be easily and rapidly adapted to different requirements. Surprisingly, it was found that an adsorption machine having the pressure-reducing element is universally usable and can be operated at different sites and varying outside temperatures. The pressure-reducing element preferably reduces the nominal width or cross-section of the free flow of at least one pipe, said element being either self-regulating or regulatable. Furthermore, it was found that the element can be retrofitted in adsorption machines at low cost, i.e., a machine can advantageously be supplemented easily and inexpensively with one or more elements. It was also surprising to find that, owing to the pressure-reducing element and splitting of the volume flows, the components of the adsorption machine comprising adsorber or condenser require less maintenance work because the components are used more efficiently and gently.

The invention also relates to a method for splitting volume flows in a sorption machine, wherein a total volume flow from a recooling unit is split into at least two volume flows, and a first volume flow flows through at least one pipe of a first pipe section into a condenser, and a second volume flow flows through at least one pipe of a second pipe section into an adsorber, and wherein at least one of the two pipes or pipe sections coming from or leading back to the recooling means has at least one pressure-reducing element and the two pipe sections have substantially different pressure loss coefficients. By integrating a pressure-reducing element, easy splitting of the volume flows preferably between adsorber and condenser is possible. On the other hand, it may also be preferred to have identical pressures or pressure loss coefficients in both lines or pipe sections. Advantageously, the volume flow between adsorber and condenser is split in such a way that the two volume flows, or pipe sections, have substantially different pressure losses or pressure loss coefficients. It was completely surprising to find that splitting and influencing or adapting or adjusting the volume flows and adapting or adjusting the pressure loss coefficients can be achieved by at least one pressure-reducing element and that the efficiency of a sorption machine, preferably an adsorption machine, is improved in this way. Without intending to be limiting, the invention will be explained in more detail below with reference to the Figures wherein

FIG. 1 shows recooling lines of an adsorption heat pump;

FIG. 2 shows pressure-reducing elements in the recooling lines;

FIG. 3 shows pressure-reducing elements in the recooling lines, taking account of the heat source line.

FIG. 1 shows typical recooling lines of an adsorption heat pump as disclosed in the prior art. The recooling lines represent the pipes 9 or lines or pipe sections coming from the recooler 11, and the arrows shown represent the preferred flow direction of the heat-carrying fluid. Following adsorption of the refrigerant, energy in the form of heat is transferred from the refrigerant to the heat-carrying fluid, e.g. water. Thereafter, the heated heat-carrying fluid requires cooling because otherwise the thermodynamic process of heat transfer would come to a halt, in which case the refrigerant is difficult to adsorb. For example, cooling the heat carrier can be effected in a recooler 11 wherein the heat of the heat carrier is transferred to another heat recipient. For example, air (a stream of air 10) or water (dry or wet cooling technology) can be used as potential heat recipient. The cooled heat carrier flows out of the recooler 11 through the pipes 9 or pipe sections (two lines) and parallel into the adsorber 13 and condenser 14, during which process the heat carrier volume flow is split, but the total volume flow remains constant. Further, a heat source 12 can be connected to the heat carrier circulation. The optional connection of heat source 12 is illustrated in the form of dashed lines. The dashed lines, as well as the continuous lines, represent pipes 9 or pipe lines. After having absorbed heat in the adsorber 13, the heat carrier preferably flows into the heat source 12 to dissipate the heat therein. The heat can be used for air conditioning, for example. Depending on the pressure loss arising inside the adsorber 13 and condenser 14 and the associated pipe sections and hydraulic components (e.g. valves) 16, the volume flow is distributed over both lines in such a way that the same pressure loss is present in both lines, i.e. in adsorber 13 and condenser 14. Consequently, the volume flow can be split via the pressure loss between adsorber 13 and condenser 14. However, this is a very imprecise method that can only be optimized empirically. Moreover, when using the line pressure loss layout, adjustment of the volume flows to a specific operating point will be insufficient; intentional fine adjustment is not possible because e.g. commercial pipe nominal widths or valve sizes are only available in grades with respect to diameters. Optimum splitting of the volume flows cannot be achieved in this way.

FIG. 2 shows pressure-reducing elements integrated in the recooling lines. After cooling the heat-carrying fluid in recooler 11 preferably by means of an air stream 10, the heat carrier flows into the adsorber 13 and condenser 14. In adsorber 13 the heat carrier preferably absorbs heat from the adsorbed refrigerant and thus accelerates adsorption thereof. In condenser 14 the heat carrier can catalyze condensation of refrigerant and likewise absorb heat therefrom. To adapt the heat carrier volume flows from recooler 11 preferably to the mode of operation of the sorption machine, in particular adsorption machine, at least one pressure-reducing element 15 is integrated in one or more pipes 9 or pipe sections, so that the pipe sections have different pressure loss coefficients. It is preferred to mount at least one element 15 in at least one pipe 9 from recooler 11, or in a pipe section or pipe line, and it may also be advantageous to mount a pressure-reducing element 15 in each of the two pipe lines or install a plurality of pressure-reducing elements 15 in the lines from the adsorber 13 or condenser 14. In this way it is possible to vary the volume flow flowing into the adsorber 13 and condenser 14. That is, adsorber 13 and condenser 14 can preferably be adapted to the mode of operation of the sorption machine, or adsorption machine, and thus cooled differently. Owing to this simple, yet effective adjustment of the volume flows, substantial improvement in efficiency is possible. As a result of integrating the pressure-reducing elements 15, the volume flows flowing into the adsorber 13 and condenser 14 have substantially different pressure losses. Advantageously, the pressure-reducing elements 15 can be integrated in each pipe 9 of a sorption machine, especially adsorption machine.

FIG. 3 shows pressure-reducing elements in the recooling lines, taking account of the heat source line. Following cooling in recooler 11 preferably by an air stream 10, the heat-carrying fluid flows through the pipes 9 and into the adsorber 13 and condenser 14. Adsorber 13 and condenser 14 are preferably connected in parallel, but may also be connected in series. The cooled heat-carrying fluid receives heat from a refrigerant in adsorber 13 and condenser 14 and is subsequently cooled by the recooler 11 by dissipation of absorbed heat to a heat recipient. On the other hand, it may be preferred to pass the heated heat-carrying fluid, after absorption of heat, to a heat source 12 to dissipate heat therein. The heat source 12, i.e. the dissipated heat, can be used for air conditioning in buildings, for example. Advantageously, the heat source 12 is separated from the heat carrier fluid circulation by hydraulic components 16 and can be switched in, if required. Hydraulic components comprise valves, ballcocks or pumps. As can be seen, it is possible to pass the heated heat-carrying fluid either to the recooler 11 or to the heat source 12. On the other hand, passage of only the heated heat-carrying fluid from adsorber 13 rather than condenser 14 to the heat source 12 can be advantageous. Advantageously, pressure-reducing elements 15 can be integrated in the line from recooler 11 upstream of adsorber 13 and/or condenser 14. After passage through heat source 12, the heat-carrying fluid advantageously does not flow through the pressure-reducing elements 15, i.e., the hydraulic component 16 is preferably arranged in such a way that the heat-carrying fluid coming from the heat source 12 flows directly into the adsorber 13. Furthermore, it may be preferred to install pressure-reducing elements 15 in the line(s) from the adsorber 13 and/or condenser 14.

KEY TO THE DRAWINGS

-   9 Pipes -   10 Air stream -   11 Recooler -   12 Heat source -   13 Adsorber -   14 Condenser -   15 Pressure-reducing element -   16 Hydraulic components 

1. Method for splitting volume flows in a sorption machine comprising splitting a total volume flow from a recooling unit into at least two volume flows, a first volume flow flowing through at least one pipe of a first pipe section into a condenser, and a second volume flow flowing through at least one pipe of a second pipe section into an adsorber, wherein at least one of the two pipes come from or lead back to the recooling unit having at least one pressure-reducing element.
 2. The method of claim 1, wherein the two pipe sections have substantially different pressure loss coefficients.
 3. The method of claim 1, wherein the adsorber and condenser are heat exchangers.
 4. The method of claim 1, wherein the volume flow is a heat-carrying fluid comprising water.
 5. The method of claim 1, wherein the pressure-reducing element is a throttle, a valve or a stopcock.
 6. The method of claim 1, wherein the pressure-reducing element is a shutter and/or a mounting part.
 7. The method of claim 1, wherein the pressure-reducing element is adjustable and variable.
 8. The method of claim 1, wherein the pressure-reducing element alters the cross-section of free flow in such a way that volume flows having different and/or equal pressures are present in the heat exchanger.
 9. The method of claim 1, wherein said at least one measuring and/or regulating device is mounted between recooler and adsorber and/or condenser.
 10. Method for splitting volume flows according to claim 1, wherein said sorption machine is an adsorption machine.
 11. The method of claim 10, wherein the two pipe sections have substantially different pressure loss coefficients.
 12. A method for splitting volume flows in a sorption machine comprising splitting a total volume flow from a recooling unit into at least two volume flows, a first volume flow flowing through at least one pipe of a first pipe section into a condenser, and a second volume flow flowing through at least one pipe of a second pipe section into an adsorber, wherein at least one of the two pipes come from or lead back to the recooling unit has at least one pressure-reducing element, so that the ratio of the pressure loss coefficients in both pipe sections can be influenced.
 13. The method of claim 2, wherein the adsorber and condenser are heat exchangers. 